Design, fabrication and characterization of tunable perfect absorber on flexible substrate

This paper reports our recent progress on a highly flexible dynamic perfect absorber at terahertz (THz) frequencies. Metamaterial unit cells were patterned on thin GaAs patches, which were fashioned in an array on a 5μm polyimide substrate via transfer printing technique, and the backside of the substrate was coated with gold film as ground plane. Optical-pump THz-probe reflection measurements show that the absorptivity at resonance frequency of 1.58THz can be tuned up to 57% through photo-excitation of free carriers in GaAs layers in presence of 800nm pump beam. Our flexible tunable MM perfect absorber exhibits potential applications in energy harvesting, imaging and stealth coating.